Space shuttle Challenger
Space shuttle Challenger detonated 73 seconds after liftoff at 11:38 a.m. Jan. 28, 1986, killing all seven astronauts aboard. Among the dead: teacher Christa McAuliffe, NASA’s first — and last — “citizen in space.” The last known words from the flight deck were recorded at the moment Challenger exploded. “Uh-oh,” pilot Michael Smith said. From Houston, launch commentator Steve Nesbitt told the world: “Obviously, a major malfunction.” The explosion on that frigid morning was blamed on a faulty “O-ring” that linked segments of one of the twin booster rockets. Investigators said the insulating ring, made rigid by the cold, cracked and allowed fiery rocket exhausts to leak and ignite the external fuel tank.a presidential commission concluded that NASA ignored repeated warnings about the O-rings and maintained a “silent safety” program that concealed problems from top managers. Though several NASA and Morton Thiokol officials resigned or were transferred, blame was never affixed to any individual.